1. What is Average Atomic Mass?

The average atomic mass is the weighted average of the atomic masses of all naturally occurring isotopes of an element, taking into account their relative abundances.

2. How Does the Calculator Work?

The calculator uses the average atomic mass formula:

Where:

• \( \text{abundance} \) — Natural abundance of each isotope (%)
• \( \text{isotope} \) — Atomic mass of each isotope (amu)

Explanation: The equation calculates a weighted average where more abundant isotopes contribute more to the final average mass.

3. Importance of Average Atomic Mass

Details: The average atomic mass is crucial for chemical calculations and appears on the periodic table. It determines the molar mass of elements used in stoichiometric calculations.

4. Using the Calculator

Tips: Enter the mass and natural abundance for each isotope. The abundances must sum to 100%. For elements with more than two isotopes, you can calculate them sequentially.

5. Frequently Asked Questions (FAQ)

Q1: Why don't abundances always sum to exactly 100%?
A: Some elements have very rare isotopes that may be omitted in basic calculations. Always use the most complete data available for precise work.

Q2: How precise should the input values be?
A: For most purposes, 4 decimal places for mass and 2 for abundance are sufficient. Research applications may require higher precision.

Q3: Can I calculate for more than two isotopes?
A: Yes, simply extend the calculation to include all isotopes. The formula generalizes to any number of isotopes.

Q4: Why is average atomic mass not a whole number?
A: It's a weighted average of different isotope masses, which themselves are not whole numbers (except by definition for carbon-12).

Q5: How does this differ from mass number?
A: Mass number is the sum of protons and neutrons in a specific isotope (always a whole number), while average atomic mass considers all isotopes.